Method for reliable control of high rotor pole switched reluctance machine

ABSTRACT

A system and method for reliable control of a high rotor pole switched reluctance machine (HRSRM) utilizing a sensorless reliable control system. The method comprising: energizing at least one of the plurality of stator phases; measuring a first current value and time taken by the first current value to reach a first peak value or preset threshold value of current; determining a self-inductance value; measuring a second current value and time taken by an adjacent un-energized stator phase to reach a second peak value of current; determining a mutual inductance value; and estimating a rotor position utilizing the self-inductance and mutual inductance values; and controlling the HRSRM based on the estimated rotor position.

RELATED APPLICATIONS

This application is a Continuation Application of U.S. patentapplication Ser. No. 15/413007 filed Jan. 23, 2017, now U.S. Pat. No.9,813,006 granted Nov. 7, 2017, which is a continuation of U.S. patentapplication Ser. No. 15/016084 filed Feb. 4, 2016, now U.S. Pat. No.9,553,538 granted Jan. 24, 2017, and which claims priority from the U.S.provisional application Ser. No. 62/111781, was filed on Feb. 4, 2015.These applications are incorporated herein by reference as if set out infull.

BACKGROUND OF THE DISCLOSURE Technical Field of the Disclosure

The present disclosure relates in general to reliable control of highrotor pole switched reluctance machine (HRSRM), and more particularly toa system and method for eliminating the use of position sensors in HRSRMwhich improve the accuracy of rotor position estimation utilizing acombination of self-inductance and mutual-inductance values.

Description of the Related Art

A wide variety of methods have been developed to provide optimal controlstrategies for switched reluctance machines (SRMs). Compared toconventional induction and synchronous motor drive systems, SRM drivesare relatively simple in construction, offer wide speed rangecapabilities and are economic to manufacture. Further, because of theabsence of windings and permanent magnets on the rotor they areattractive for robust and harsh environment applications. In addition,the converter, which applies power to the SRM drive, often requiresfewer power devices and, therefore, is more economical and reliable.Building on these advantages, SRM drive systems provide an advancedalternative to conventional drive systems in several variable speeddrive and industrial applications. SRM drives conventionally havemultiple poles on both the stator and rotor. The stator includes phasewindings, but the rotor does not include windings or magnets.

In an SRM system, the stator generates torque on the rotor when thecurrent passing through each phase winding is switched on in apredetermined sequence. By properly positioning the firing pulsesrelative to the rotor angle, forward or reverse operations may beobtained. Usually, the desired phase current commutation is achieved byfeeding back a rotor position signal to a controller from a shaftposition sensor, e.g., an encoder or resolver. For economic reasons insmall drives and reliability reasons in larger drives and to reducesize, weight, and inertia in all such drives, it is desirable toeliminate this shaft position sensor. In order to overcome thisshortcoming, a new sensorless technique for high rotor pole switchedreluctance machine (HRSRM) has been introduced.

Compared to a conventional SRM, the HRSRM exhibits higher static torquecapabilities, which effectively addresses torque ripple and acousticnoise problems. The design parameters of the power converters aredifferent in HRSRMs vs. HRMs. This is because the HRSRM has a differentinductance profile and a higher number of strokes. Most reliabletechniques for conventional HRSRM operation utilize the self-inductanceof the phase coil to estimate position. The HRSRM has a higher number ofrotor poles for the same circumference as a conventional SRM. The highernumber of rotor poles reduces the angular travel per excitation. HRSRMhas shown an approximate increase of 83% in static torque capabilitiesas compared to a 6/4 SRM under steady state operations for the samejoule losses. However, the larger number of rotor poles leads to asmaller gap and the arc length (or angular length) between two rotorpoles is smaller. Consequently, unaligned inductance of the machine islower and the resultant the self-inductance profile for the HRSRM tendsto become flatter, which leads to unreliable position estimations. Thus,the use of self-inductance of the phase coil alone is often notsufficient to estimate the accurate rotor position in the HRSRM.

Several methods have been developed to solve the above shortcomings. Oneof the existing reliable control methods includes a technique formeasuring mutual inductance. In a first example embodiment of thistechnique, a voltage pulse is applied to the primary coil when themachine is stationary. By measuring current in the primary coil andmeasuring induced voltages in adjacent open circuited coils, mutualinductance may be determined. In another example embodiment, a voltagepulse is applied to the primary coil when the machine is stationary. Thesecondary coil is allowed to free-wheel current through the phase. Bymeasuring the time taken by the primary phase to reach a peak or presetthreshold value, the mutual inductance for the known position of a rotormay be determined. However, this technique usually does not provide anaccurate estimation of rotor position since this method only utilizesmutual inductance for the rotor position estimation.

Some other reliable control methods include a controller that implementsa model of at least one active phase representing dynamic magneticmachine characteristics. The controller determines machine controlsignals based on rotational position obtained by numerically solving themodel with measured machine operating parameters. The model may beimplemented as the sum of orthogonal functions relating active phasevoltage and current with constants derived from phase inductance toobtain the rotor angle. Yet another reliable control method includesprobing a selected diagnostic phase with a pulse injection process;measuring an actual operating characteristic of the SRM; computing aninductance based on the actual operating characteristic and correlatingthe inductance with a position to formulate an estimated position;modeling the SRM to formulate an observer-based estimated position;selecting one of the estimated positions, the observer-based estimatedposition, and a combination thereof to formulate a selected position ofthe SRM; and controlling said SRM based on said selected position and acommand. However, in most of these methods, while evaluating the machineperformance, the mutual inductances between phases are neglected,resulting in an unreliable position estimation. Further, these methodsdo not provide an accurate rotor position in a HRSRM configuration.

Therefore, there is a need for a method of reliable control of a HRSRMusing a combination of self-inductance and mutual inductance to enhancethe accuracy of rotor position estimation. The method would use onlyterminal measurements such as, voltages, currents and time and would notrequire additional hardware or memory. Further, the method would be ableto accurately estimate instantaneous rotor position in HRSRM and SRM,irrespective of motor speed or direction, and without resorting to arotor position sensor. Finally, the method would be reliable, robust andpreferably cost effective. The present embodiment accomplishes theseobjectives.

SUMMARY OF THE DISCLOSURE

To minimize the limitations found in the prior art and to minimize otherlimitations that will be apparent upon the reading of thisspecification, the Applicant provides a sensorless reliable controlsystem for a high rotor pole switched reluctance machine (HRSRM). Thepresent reliable control system utilizes electrical parameters such ascurrent and voltage to determine rotor position with high accuracythereby eliminating the required use of shaft position sensors. TheHRSRM includes a rotor and a stator with a plurality of stator phaseseach having a winding. The reliable control system includes a statorphase energizing module to excite at least one of the plurality ofstator phases, wherein each of the windings of the rest of the pluralityof stator phases is in an open circuit state. A first current and timemeasuring module measures a first current value through the at least oneenergized stator phase taken by the first current value to reach a firstpeak value of current. The system further comprises a self-inductancedetermining module to determine the self-inductance value for the atleast one energized stator phase utilizing the first current value andtime. A first storage module stores the determined self-inductance valueand the first current value for each of the plurality of stator phasesin a lookup table or alternatively the self-inductance and currentvalues are stored in the form of an analytical expression such as apolynomial or Fourier expression that describes the inductance of eachphase at each current value. A second current and time measuring modulemeasures a second current value through an adjacent un-energized statorphase and the time taken by the adjacent un-energized stator phase toreach a second peak value of current wherein the winding of the adjacentstator phase is in an open circuit state. A mutual-inductancedetermining module determines the mutual inductance value between the atleast one energized stator phase and the adjacent un-energized statorphase. A second storage module stores the mutual inductance value andthe second current value for each of the plurality of stator phases inthe lookup table or in the form of an analytical expression such as apolynomial or Fourier expression that describes the inductance of eachphase at each current value. A rotor position estimation moduleestimates a rotor position utilizing a combination of theself-inductance and mutual inductance values determined at theself-inductance determining module and the mutual-inductance determiningmodule respectively. A control module controls the HRSRM utilizing theestimated rotor position.

The preferred method provides a method for reliable control of a highrotor pole switched reluctance machine (HRSRM) utilizing the sensorlessreliable control system, the method comprising: energizing at least oneof the plurality of stator phases at a stator phase energizing module,wherein each of the windings of the rest of the plurality of statorphases is in an open circuit state; measuring a first current valuethrough the at least one energized stator phase and the time taken bythe first current value to reach a first peak value of current at afirst current and time measuring module; determining a self-inductancevalue for the at least one energized stator phase at a self-inductancedetermining module; storing the self-inductance value and the firstcurrent value for each of the plurality of stator phases at a firststorage module; measuring a second current value through an adjacentun-energized stator phase and time taken by the adjacent un-energizedstator phase to reach a second peak value of current at a second currentand time measuring module, wherein the winding of the adjacentun-energized stator phase is in an open circuit state; determining amutual inductance value between the at least one energized stator phaseand the adjacent un-energized stator phase at a mutual-inductancedetermining module; storing the mutual inductance value and the secondcurrent value for each of the plurality of stator phases at a secondstorage module; estimating a rotor position utilizing a combination ofthe stored self-inductance and mutual inductance values at a rotorposition estimation module; and controlling the HRSRM based on theestimated rotor position at a control module.

In another configuration of the preferred embodiment, the mutualinductance is determined utilizing a voltage and time values. In thisconfiguration, the reliable control system includes the stator phaseenergizing module to excite the at least one of the plurality of statorphases, wherein each of the windings of the rest of the plurality ofstator phases is in an open circuit state. The current value through theat least one energized stator phase and time taken by the current valueto reach a peak value of current are measured at a current and timemeasuring module. The self-inductance value for the at least oneenergized stator phase is determined at a self-inductance determiningmodule. The self-inductance value and the current value for each of theplurality of stator phases are stored at the first storage module. Themagnitude of voltage value across an adjacent un-energized stator phaseand time taken by an adjacent un-energized stator phase to attain thevoltage value are measured at a voltage and time measuring module,wherein the winding of the adjacent un-energized stator phase is in ashort circuit state. The mutual inductance value between the at leastone energized stator phase and the adjacent un-energized stator phase isdetermined at a mutual-inductance determining module. In the secondstorage module, the mutual inductance and the voltage value for each ofthe plurality of stator phases are stored. The rotor position isestimated utilizing the hybrid combination of the estimatedself-inductance and mutual inductance values at the rotor positionestimation module. The control module controls the HRSRM based on theestimated rotor position.

In one embodiment, the method for the above-mentioned configuration ofthe reliable control system comprises energizing at least one of theplurality of stator phases at a stator phase energizing module, whereineach of the windings of the rest of the plurality of stator phases is inan open circuit state; measuring a current value through the at leastone energized stator phase and time taken by the current value to reacha peak value of current at a current and time measuring module;determining a self-inductance value for the at least one energizedstator phase at a self-inductance determining module; storing theself-inductance value and the current value for each of the plurality ofstator phases at a first storage module; measuring a voltage valueacross an adjacent un-energized stator phase and time taken by anadjacent un-energized stator phase to attain the voltage value at avoltage and time measuring module, wherein the winding of the adjacentun-energized stator phase is in a short circuit state; determining amutual inductance value between the at least one energized stator phaseand the adjacent un-energized stator phase at a mutual-inductancedetermining module; storing the mutual inductance and the voltage valuefor each of the plurality of stator phases at a second storage module;estimating a rotor position utilizing a combination of the storedself-inductance and mutual inductance values at a rotor positionestimation module; and controlling the HRSRM based on the estimatedrotor position at a control module.

A first objective of the present invention is to provide a system andmethod for reliable control of a HRSRM that enhances the accuracy ofrotor position estimation by using a combination of self-inductance andmutual inductance values.

A second objective of the present invention is to provide a system andmethod for reliable control of the HRSRM that eliminates the use of arotor position sensor and the added weight and space requirementsattendant thereto.

A third objective of the present invention is to provide a method andsystem for the reliable control of the HRSRM that utilizes only terminalmeasurements such as voltages, currents and time without requiring anyadditional hardware.

Another objective of the present invention is to provide a method andsystem for reliable control of the HRSRM that is cost effective,reliable and robust.

These and other advantages and features of the present invention aredescribed with specificity so as to make the present inventionunderstandable to one of ordinary skill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Elements in the figures have not necessarily been drawn to scale inorder to enhance their clarity and improve the understanding of thevarious elements and embodiments of the invention. Furthermore, elementsthat are known to be common and well understood to those in the industryare not depicted in order to provide a clear view of the variousembodiments of the invention, thus the drawings are generalized in formin the interest of clarity and conciseness.

FIG. 1 illustrates a block diagram of a sensorless reliable controlsystem for a high rotor pole switched reluctance machine (HRSRM) inaccordance with one embodiment of the present invention;

FIG. 2 illustrates a flowchart of a method for reliable control of theHRSRM utilizing the sensorless reliable control system for the HRSRMshown in FIG. 1;

FIG. 3 illustrates a block diagram of another configuration of thesensorless reliable control system for the HRSRM in accordance with oneembodiment of the present invention;

FIG. 4 illustrates a flowchart of a method for the sensorless reliablecontrol system shown in FIG. 3;

FIG. 5 illustrates a converter setup to implement the sensorlessreliable control system shown in FIG. 1;

FIG. 6 illustrates a converter setup to implement the sensorlessreliable control system shown in FIG. 3; and

FIG. 7 illustrates a system layout for the sensorless control of theHRSRM utilizing current measurements to estimate the rotor position inaccordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

In the following discussion that addresses a number of embodiments andapplications of the present invention, reference is made to theaccompanying drawings that form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. It is to be understood that other embodiments may be utilizedand changes may be made without departing from the scope of the presentinvention.

Various inventive features are described below that can each be usedindependently of one another or in combination with other features.However, any single inventive feature may not address any of theproblems discussed above, may only address one of the problems discussedabove, or may address multiple problems discussed above. Further, one ormore of the problems discussed above may not be fully addressed by anyof the features described below.

The present embodiment provides a sensorless reliable control system 10for a high rotor pole switched reluctance machine (HRSRM) 12 utilizing ahybrid combination of self-inductance and mutual inductance values asshown in FIG. 1. The HRSRM 12 includes a rotor 14 and a stator 16 with aplurality of stator phases each having a winding. The reliable controlsystem 10 comprises a stator phase energizing module 18 to excite atleast one of the plurality of stator phases, wherein each of thewindings of the rest of the plurality of stator phases is in an opencircuit state. A first current and time measuring module 20 measures afirst current value through the at least one energized stator phasetaken by the first current value to reach a first peak value of current.The system 10 further comprises a self-inductance determining module 22to determine a self-inductance value for the at least one energizedstator phase utilizing the first current value and time. A first storagemodule 24 stores the determined self-inductance value and the firstcurrent value for each of the plurality of stator phases in a lookuptable or alternatively stored in the form of an analytical expressionsuch as a polynomial or Fourier expression that describes the inductanceof each phase at each current value. A second current and time measuringmodule 26 measures a second current value through an adjacentun-energized stator phase and time taken by the adjacent un-energizedstator phase to reach a second peak value of current, wherein thewinding of the adjacent stator phase is in an open circuit state. Thesystem further comprises a mutual-inductance determining module 28 todetermine a mutual inductance value between the at least one energizedstator phase and the adjacent un-energized stator phase. A secondstorage module 30 stores the mutual inductance value and the secondcurrent value for each of the plurality of stator phases in the lookuptable or in the form of an analytical expression (a polynomial orFourier expression that describes the inductance of each phase at eachcurrent value). A rotor position estimation module 32 of the reliablecontrol system 10 is designed to estimate a rotor position utilizing acombination of the self-inductance and mutual inductance valuesdetermined at the self-inductance determining module and themutual-inductance determining module respectively. The reliable controlsystem 10 further comprises a control module 34 to control the HRSRMutilizing the estimated rotor position.

FIG. 2 illustrates a flowchart of a method for reliable control of theHRSRM 12 utilizing the sensorless reliable control system 10. The methodis designed to control the HRSRM with high accuracy. The preferredmethod commences by providing the HRSRM with the rotor and the stator asshown in block 42. The at least one of the plurality of stator phases isenergized at the stator phase energizing module, wherein each of thewindings of the rest of the plurality of stator phases is in the opencircuit state as shown in block 44. Next, the first current valuethrough the at least one energized stator phase and the amount of timetaken by the first current value to reach the first peak value ofcurrent are determined at the first current and time measuring module asshown in block 46. Then, the self-inductance value for the at least oneenergized stator phase is determined at the self-inductance determiningmodule as indicated at block 48. Thereafter, the first storage modulestores the self-inductance value and the first current value for each ofthe plurality of stator phases in the lookup table or stores in the formof an analytical expression as shown in block 50. The second currentvalue through the adjacent un-energized stator phase and time taken bythe adjacent un-energized stator phase are measured at the secondcurrent and time measuring module as indicated at block 52, wherein thewinding of the adjacent un-energized stator phase is in an open circuitstate. Next, the mutual inductance value between the at least oneenergized stator phase and the adjacent un-energized stator phase aredetermined at the mutual-inductance determining module as indicated atblock 54. The second storage module stores the mutual inductance valueand the second current value in the lookup table or in the form of ananalytical expression as shown in block 56. Thereafter, the rotorposition is estimated utilizing the hybrid combination of theself-inductance and mutual inductance values at the rotor positionestimation module as shown in block 58. Finally, the estimated rotorposition is utilized to control the HRSRM at the control module asindicated at block 60.

Since one or more of the phase windings in this embodiment is switchedoff at any given time, it is possible to probe that winding with a lowlevel signal and determine its input impedance. This information,together with the knowledge of the functional relationship betweeninductance and rotor position, makes it possible to determine a highlyaccurate angular position of the rotor 14 from electrical measurementssuch as voltage and current, thereby eliminating the need for a shaftposition sensor.

Another configuration of the preferred embodiment is shown in FIG. 3. Inthis configuration, the mutual inductance is determined utilizingvoltage and time values. The reliable control system 10 includes thestator phase energizing module 18 to excite the at least one of theplurality of stator phases, wherein each of the windings of the rest ofthe plurality of stator phases is in an open circuit state. A currentand time measuring module 36 measures the current value through the atleast one energized stator phase and the time taken by the current valueto reach the peak value of current. The self-inductance determiningmodule 22 determines the self-inductance value for the at least oneenergized stator phase. The first storage module 24 stores theself-inductance value and the current value for each of the plurality ofstator phases in the lookup table or in an analytic expression. Avoltage and time measuring module 38 measures a voltage value across anadjacent un-energized stator phase and the time taken by the adjacentun-energized stator phase to attain the voltage value, wherein thewinding of the adjacent un-energized stator phase is in a short circuitstate. The mutual-inductance determining module 28 utilizes thedetermined voltage and time values to evaluate the mutual inductancevalue between the at least one energized stator phase and the adjacentun-energized stator phase. The second storage module 30 stores themutual inductance value and the voltage value for each of the pluralityof stator phases. The rotor position estimation module 32 estimates therotor position utilizing a combination of the stored self-inductance andmutual inductance values. Based on the estimated rotor position, thecontrol module 34 controls the HRSRM.

FIG. 4 illustrates a flowchart of a method for reliable control of theHRSRM utilizing the sensorless reliable control system shown in FIG. 3.The method starts by providing a HRSRM including a rotor and a statorwith a plurality of stator phases as indicated at block 62. Next, thestator phase energizing module energizes at least one of the pluralityof stator phases, wherein each of the windings of the rest of theplurality of stator phases is in the open circuit state as shown inblock 64. Thereafter, the current and time taken by the current value toreach the peak value of current is measured at the current and timemeasuring module as shown in block 66. The self-inductance determiningmodule determines the self-inductance value for the at least oneenergized stator phase as shown in block 68. Next, the first storagemodule stores the self-inductance value and the current value for eachof the plurality of stator phases in the lookup table or in the form ofan analytical expression as shown in block 70. As shown in block 72, thevoltage value across an adjacent un-energized stator phase and the timetaken by an adjacent un-energized stator phase are measured to attainthe voltage value at the voltage and time measuring module, wherein thewinding of the adjacent un-energized stator phase is in the shortcircuit state. The mutual inductance value between the at least oneenergized stator phase and the adjacent un-energized stator phase isdetermined at the mutual-inductance determining module as indicated atblock 74. Next, the mutual inductance and the voltage value for each ofthe plurality of stator phases are stored at the second storage moduleas shown in block 76. Thereafter, the rotor position is estimatedutilizing the hybrid combination of the stored self-inductance andmutual inductance values at the rotor position estimation module asindicated at block 78. Finally, the estimated rotor position is utilizedto control the HRSRM at the control module as shown in block 80.

During operation, any of the currently existing techniques areimplemented to measure self and mutual inductance values. In analternative embodiment, a combination of self-inductance and the backEMF from the HRSRM 12 or back EMF and mutual inductance from the HRSRM12 are used to determine the rotor position.

FIG. 5 is a diagrammatic converter setup 82 to implement the sensorlessreliable control system 10 shown in FIG. 1. This electrical circuitarrangement measures the self-inductance for phase A and themutual-inductance for open-circuited phase B.

FIG. 6 is a diagrammatic converter setup 84 to implement the sensorlessreliable control system 10 shown in FIG. 3. This electrical circuitarrangement measures the self-inductance for phase A and themutual-inductance for short-circuited phase B.

FIG. 7 is a diagrammatic system layout 86 for the sensorless reliablecontrol system 10 using current measurements to estimate the rotorposition. This electrical arrangement utilizes a gate driver circuit 88and a computer system 90 to control the electrical inputs to theplurality of stator phase windings.

The foregoing description of the preferred embodiment of the presentinvention has been presented for the purpose of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise form disclosed. Many modifications andvariations are possible in light of the above teachings. It is intendedthat the scope of the present invention not be limited by this detaileddescription, but by the claims and the equivalents to the claimsappended hereto.

What is claimed is:
 1. A method for reliable control of a high rotorpole switched reluctance machine (HRSRM), the method comprising thesteps of: (a) providing an HRSRM comprising a rotor and a stator with aplurality of stator phases each having a winding; (b) energizing atleast one of the plurality of stator phases at a stator phase energizingmodule, wherein each of the windings of the rest of the plurality ofstator phases is in an open circuit state; (c) measuring a current valuethrough the at least one energized stator phase and time taken by thecurrent value to reach a peak value or preset magnitude of current at acurrent and time measuring module; (d) determining a self-inductancevalue for the at least one energized stator phase at a self-inductancedetermining module; (e) measuring a voltage value across an adjacentun-energized stator phase and time taken by an adjacent un-energizedstator phase to attain the voltage value at a voltage and time measuringmodule, wherein the winding of the adjacent un-energized stator phase isin a short circuit state; and (f) determining a mutual inductance valuebetween the at least one energized stator phase and the adjacentun-energized stator phase at a mutual-inductance determining module. 2.The method of claim 1 wherein the self-inductance value and the currentvalue are stored in a look up table at a first storage module.
 3. Themethod of claim 1 wherein the self-inductance value and the currentvalue are stored in a form of an analytical expression at a storagemodule.
 4. The method of claim 1 wherein the mutual-inductance value andthe voltage value are stored in a look up table at a storage module. 5.The method of claim 1 wherein the mutual-inductance value and thevoltage value are stored in the form of an analytical expression at astorage module.
 6. A method for reliable control of a high rotor poleswitched reluctance machine (HRSRM), the method comprising the steps of:(a) providing an HRSRM comprising a rotor and a stator with a pluralityof stator phases each having a winding; (b) energizing at least one ofthe plurality of stator phases at a stator phase energizing module,wherein each of the windings of the rest of the plurality of statorphases is in an open circuit state; (c) measuring a first current valuethrough the at least one energized stator phase and time taken by thefirst current value to reach a first peak value or preset magnitude ofcurrent at a first current and time measuring module; (d) determining aself-inductance value for the at least one energized stator phase at aself-inductance determining module; (e) measuring a second current valuethrough an adjacent un-energized stator phase and time taken by theadjacent un-energized stator phase to reach a second peak value ofcurrent at a second current and time measuring module, wherein thewinding of the adjacent un-energized stator phase is in an open circuitstate; and (f) determining a mutual inductance value between the atleast one energized stator phase and the adjacent un-energized statorphase at a mutual-inductance determining module.
 7. The method of claim6 wherein the self-inductance value and the first current value arestored in a look up table at a storage module.
 8. The method of claim 6wherein the self-inductance value and the first current value are storedin a form of an analytical expression at a storage module.
 9. The methodof claim 6 wherein the mutual-inductance value and the second currentvalue are stored in a look up table at a storage module.
 10. The methodof claim 6 wherein the mutual-inductance value and the second currentvalue are stored in the form of an analytical expression at a storagemodule.
 11. A high rotor pole switched reluctance machine comprising: arotor and a stator with a plurality of stator phases each having awinding; a stator phase energizing module to excite at least one of theplurality of stator phases, wherein each of the windings of the rest ofthe plurality of stator phases is in an open circuit state; a firstcurrent and time measuring module to measure a first current valuethrough the at least one energized stator phase and time taken by thefirst current value to reach a first peak value of current; aself-inductance determining module to determine a self-inductance valuefor the at least one energized stator phase; a second current and timemeasuring module to measure a second current value through an adjacentun-energized stator phase and time taken by the adjacent un-energizedstator phase to reach a second peak value of current, wherein thewinding of the adjacent un-energized stator phase is in an open circuitstate; and a mutual-inductance determining module to determine a mutualinductance value between the at least one energized stator phase and theadjacent un-energized stator phase.
 12. The sensorless reliable controlsystem of claim 11 wherein the self-inductance and the first currentvalues are stored in a lookup table at a storage module.
 13. Thesensorless reliable control system of claim 11 wherein theself-inductance and the first current values are stored in the form ofan analytical expression at a storage module.
 14. The sensorlessreliable control system of claim 11 wherein the mutual-inductance andthe second current values are stored in the lookup table at a storagemodule.
 15. The sensorless reliable control system of claim 11 whereinthe mutual-inductance and the second current values are stored in theform of an analytical expression at a storage module.
 16. A high rotorpole switched reluctance machine comprising: a rotor and a stator with aplurality of stator phases each having a winding; a stator phaseenergizing module to excite at least one of the plurality of statorphases, wherein each of the windings of the rest of the plurality ofstator phases is in an open circuit state; a current and time measuringmodule to measure a current value through the at least one energizedstator phase and time taken by the current value to reach a peak valueor preset magnitude of current; a self-inductance determining module todetermine a self-inductance value for the at least one energized statorphase; a voltage and time measuring module to measure a voltage valueacross an adjacent un-energized stator phase and time taken by theadjacent un-energized stator phase to attain the voltage value, whereinthe winding of the adjacent un-energized stator phase is in a shortcircuit state; a mutual-inductance determining module to determine amutual inductance value between the at least one energized stator phaseand the adjacent un-energized stator phase.
 17. The sensorless reliablecontrol system of claim 16 wherein the self-inductance and the currentvalues are stored in a lookup table at a storage module.
 18. Thesensorless reliable control system of claim 16 wherein theself-inductance and the current values are stored in the form of ananalytical expression at a storage module.
 19. The sensorless reliablecontrol system of claim 16 wherein the mutual-inductance and the voltagevalues are stored in the lookup table at a storage module.
 20. Thesensorless reliable control system of claim 16 wherein themutual-inductance and the voltage values are stored in the form of ananalytical expression at a storage module.